One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(10,15)(11,17)(18,23)(19,24)(25,26,31,32)(27,34,28,33)(29,35,39,38)(30,36,40,37)(2,5)(6,7)(9,10)(11,16)(12,17)(13,18)(14,15)(19,21)(20,24)(22,23)(26,32)(27,28)(35,38)(36,37) involution — undirected(1,2)(3,6)(4,5)(7,8)(25,27,31,28)(26,33,32,34)(29,37,39,36)(30,35,40,38)(1,3,4,8)(2,6,5,7)(9,11,14,17)(10,16,15,12)(13,19,22,24)(18,21,23,20)(25,28,31,27)(26,34,32,33)(29,36,39,37)(30,38,40,35)(9,12,14,16)(10,17,15,11)(13,21,22,20)(18,19,23,24)(25,29)(26,35)(27,37)(28,36)(30,34)(31,39)(32,38)(33,40)(9,13,14,22)(10,18,15,23)(11,19,17,24)(12,20,16,21)(25,30)(26,36)(27,35)(28,38)(29,33)(31,40)(32,37)(34,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.